Solar Resource Map
Below are several links to solar radiation resource maps that DOE EERE and NREL prepare.
U.S. Solar Radiation Rescource Maps
NREL Solar Maps
NREL Concentrating Solar Power Resource Maps
As an example, below is the annual solar radiation map for the U.S. The PDF version of the map can be found by clicking here.
NREL has developed “The In My Backyard (IMBY) tool” that estimates the electricity you can produce with a PV system or wind turbine at your home or business. Homeowners, businesses, and researchers use IMBY to develop quick estimates of renewable energy production at locations throughout the continental United States, Hawaii, and northern Mexico. IMBY uses a map-based interface to allow you to choose the exact location of your PV array or wind turbine. Based on your location, system size, and other variables, IMBY estimates the electricity production you can expect from your system. Learn more about the In My Backyard tool at http://www.nrel.gov/eis/imby/about.html.